Re: leaving hookah set up
I don't see a problem with letting it sit overnight. I clean mine while my coals are heating up. I usually have plenty of time to clean the stem, bowl, vase and choose my tobacco. I swish lemon juice in the vase to get rid of any strong odor or flavor.
If it is only sitting out for a day or two, the rust shouldn't be much more than on the surface, if it rusts at all. A quick once over with your stem brush will take care of that. Corrosion actually acts as a short term protective surface on metals. As long as it remains undisturbed, it will prevent decay of steel for a short amount of time. The problem worsens when the rust is removed while still leaving pitting. This pitting will still have some of the corrosion trapped in it and it will attack the un-corroded metal. A few days will not result in pitting type corrosion, a few weeks could. So, as long as you're not leaving your hookah sit out for extended periods of time, you should be fine. And they told me being an aircraft structural maintenance craftsman would get me nowhere...
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